An EFI System Partition (ESP) is simply a FAT32 partition with a GUID type code of C12A7328-F81F-11D2-BA4B-00A0C93EC93B (or 0xEF on an MBR disk). Most partitioning tools have some other way of displaying the GUID type code, because GUIDs are so cumbersome. In parted, GParted, and most other libparted-based tools, it's shown as a "boot flag" being set on the partition. (Note, however, that in libparted-land, the "boot flag" on a GPT disk is unrelated to the "boot flag" on an MBR disk. AFAIK, libparted provides no way to correctly label an MBR ESP.) In GPT fdisk (gdisk, sgdisk, and cgdisk), an ESP has a type code of EF00. Non-Linux tools have their own ways to identify ESPs.
Thus, to create a new ESP, you would:
- Boot to any Linux tool that lets you partition the disk. This could be your existing Linux installation or an emergency disk/live CD -- but if you use your regular installation, be aware that you may be limited in what you can do, because many partitioning tools limit what you can do to a disk with partitions that are mounted.
- Launch the partitioning tool of your choice.
- If necessary, create a new partition. I recommend making it at least 550MiB in size. Note that you may need to shrink existing partition(s) to make room.
- Place a FAT32 filesystem on the partition. Some tools, such as GParted, make it possible to combine this step with the previous one.
- Mark said partition as an ESP.
- Unmark or delete the old ESP.
- If necessary, save your changes.
For making partition table changes, there's no need to be concerned with your boot mode -- you can use EFI mode or BIOS mode as you see fit. (That said, some computers make it easier to boot from USB or CD-R in one mode or another.)
I agree with oldfred that creating a new ESP is unlikely to be necessary in your scenario. If you want to completely erase the Windows boot loader from the ESP, feel free to do so -- it would be the /boot/efi/EFI/Microsoft directory tree once Ubuntu is installed. Note that this will not remove the Windows boot loader from the firmware's boot manager menu. To do that, you'll need to use efibootmgr, as in:
$ sudo efibootmgr
Timeout: 10 seconds
BootOrder: 0000,0004,0001,0002
Boot0000* rEFInd boot manager
Boot0001* PATA: HP DVD Writer 1040r
Boot0002* SATA: ST32000542AS 2
Boot0003* SATA: TOSHIBA DT01ACA300 3
Boot0004* Windows boot manager
Boot0008* INTERNAL EFI SHELL: ST32000542AS
$ sudo efibootmgr -B -b 4
This example deletes boot option #4, which is identified as "Windows boot manager." (I don't recall the name that Windows uses by default; I edited this example from one of my systems on which Windows is not installed.)
Reinstall the GRUB boot loader to your Ubuntu installation in EFI mode this way ...
Boot from the Ubuntu installation medium and select 'Try Ubuntu without installing'.
(Boot your install medium in EFI mode, select the Ubuntu entry with UEFI in front.)
Once you are on the Live desktop, open a terminal and execute these commands :
sudo mount /dev/sdXY /mnt
sudo mount /dev/sdXX /mnt/boot/efi
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo chroot /mnt
grub-install /dev/sdX
update-grub
Note : sdX = disk | sdXX = efi partition | sdXY = system partition
To identify the partitions use GParted, the tool is included in the installation medium.
After having run the commands GRUB will be installed in the separate EFI partition.
Best Answer
To begin, note that deleting the Ubuntu boot loader is not usually necessary. If you plan to re-install Ubuntu, the new installation will take over the old one's location, so deleting the old boot loader won't achieve anything. If you plan to boot some other OS that's already installed, changing the boot order (with
efibootmgrin Ubuntu or another Linux, EasyUEFI in Windows, or other similar tools) should be sufficient. The main reason to delete the old boot loader is if you've installed (or plan to install) some other OS or boot manager, and you want to keep Ubuntu's GRUB out of its menu. Beyond that, deleting Ubuntu's GRUB could qualify as "good housekeeping," but it's likely unnecessary.That said, the most reliable way to mount the EFI System Partition (ESP) from the Ubuntu installer/emergency disk is as follows:
sudo fdisk -l. This should produce output that identifies the ESP (among other things), like this:.
EFI Systemin theTypecolumn. In this example, it's/dev/sda1. (The ESP is usually/dev/sda1or/dev/sda2, but that's just what's most common.)/mnt, as insudo mount /dev/sda1 /mnt. If you prefer, you can create a mount point other than/mntand mount the ESP there. This might be necessary if you want to mount multiple partitions.You can then use
ls,cp,mv,rm, and other text-mode commands in the Terminal window. Note that, unless you add variousmountoptions, you'll need to usesudoto operate on files on the ESP.